Réponse :
Bonsoir
(x - 3)² - 25 = 0
⇔ (x - 3)² - 5² = 0
⇔ (x - 3 + 5)(x - 3 - 5) = 0
⇔ (x + 2)(x - 8) = 0
⇔ x + 2 = 0 ou x - 8 = 0
⇔ x = -2 ou x = 8
S ={-2 ; 8}
(2x - 4)² - 9x² = 0
⇔ (2x - 4)² - (3x)² = 0
⇔ (2x - 4 + 3x)(2x - 4 - 3x) = 0
⇔ (5x - 4)(-x - 4) = 0
⇔ 5x - 4 = 0 ou -x - 4 = 0
⇔ 5x = 4 ou -x = 4
⇔ x = 4/5 ou x = -4
S = {-4 ; 4/5}
(x - 4)² - 3² = 0
⇔ (x - 4 + 3)(x - 4 - 3) = 0
⇔ (x - 1)(x - 7) = 0
⇔ x = 1 ou x = 7
S = {1 ; 7}
